{
  "bibcode": "2012GCN.14105....1K",
  "body": "H. A. Krimm (CRESST/GSFC/USRA), J. R. Cummings (NASA/UMBC),\nV. D'Elia (ASDC), S. T. Holland (STScI), K. L. Page (U Leicester),\nT. Sakamoto (AGU), M. H. Siegel (PSU) and\nR. L. C. Starling (U Leicester) report on behalf of the Swift Team:\n\nAt 19:09:43 UT, the Swift Burst Alert Telescope (BAT) triggered and\nlocated GRB 121226A (trigger=544027).  Swift slewed immediately to the burst. \nThe BAT on-board calculated location is \nRA, Dec 168.658, -30.414 which is \n   RA(J2000) = 11h 14m 38s\n   Dec(J2000) = -30d 24' 51\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty).  The BAT light curve showed a single peak\nwith a duration of about 2 sec.  The peak count rate was ~2700 counts/sec\n(15-350 keV), at ~0 sec after the trigger.  Although the duration of this\nburst is moderately short, it has a fairly soft spectrum.  Therefore we must\nwait for further data to determine whether to classify GRB 121226A as\na short or long burst. \n\nThe XRT began observing the field at 19:11:24.4 UT, 100.6 seconds after\nthe BAT trigger. Using promptly downlinked data we find an uncatalogued\nX-ray source with an enhanced position: RA, Dec 168.6424, -30.4066\nwhich is equivalent to:\n   RA(J2000)  = 11h 14m 34.17s\n   Dec(J2000) = -30d 24' 23.8\"\nwith an uncertainty of 2.2 arcseconds (radius, 90% containment). This\nlocation is 55 arcseconds from the BAT onboard position, within the BAT\nerror circle. This position may be improved as more data are received;\nthe latest position is available at http://www.swift.ac.uk/sper.  We\ncannot determine whether the source is fading at the present time. \n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata gives a column density in excess of the Galactic value (6.11 x\n10^20 cm^-2, Kalberla et al. 2005), with an excess column of 6.4\n(+3.77/-3.06) x 10^21 cm^-2 (90% confidence). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 104 seconds after the BAT trigger. No credible afterglow candidate has\nbeen found in the initial data products. The 2.7'x2.7' sub-image covers 100% of\nthe XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. \nThe 8'x8' region for the list of sources generated on-board covers 100% of the\nXRT error circle. The list of sources is typically complete to about 18 mag. No\ncorrection has been made for the expected extinction corresponding to E(B-V) of\n0.05. \n\nBurst Advocate for this burst is H. A. Krimm (krimm AT milkyway.gsfc.nasa.gov). \nPlease contact the BA by email if you require additional information\nregarding Swift followup of this burst. In extremely urgent cases, after\ntrying the Burst Advocate, you can contact the Swift PI by phone (see\nSwift TOO web site for information: http://www.swift.psu.edu/too.html.)",
  "circularId": 14105,
  "createdOn": 1356549851000,
  "email": "krimm@milkyway.gsfc.nasa.gov",
  "subject": "GRB 121226A: Swift detection of a burst",
  "submitter": "Hans Krimm at NASA-GSFC  <krimm@milkyway.gsfc.nasa.gov>",
  "eventId": "GRB 121226A"
}